Favor Low SoC or Small Cycles?

[Drinyth]

Based on what I've read, I'm sold on keeping my vehicle charged to its lowest SoC that suits my driving needs for a daily basis is what works best for me. For my needs, I'm easily able to stay at 50% for a target charge level and have more than enough capacity for my driving needs.

My question is if I make multiple daily trips, is it better to constantly plug in after each trip backup to 50%? Or to just charge once per day and let my overall daily SoC remain lower?

In other words, assuming that my charge level is set to 50%, is it better to do 3-4 x 5% charges (i.e. 45% back up to 50%)? Or to do one charge overnight of 15-20% for the day? The prior keeps my charging cycle smaller but the latter keeps my battery at a lower SoC as an average?

I realize that I may be splitting hairs here in doing what I can to maintain battery health, but I don't feel it's an hassle for me at all for me to do it whatever way is best for battery longevity. I typically just make in town trips and I work from home so am easily able to plug in between trips (with the only inconvenience being to reach over and plug in the charging cable that's right next to where my car is parked).

 

[GtiMart]

I believe you are splitting hairs. Yes, it seems to be marginally better to plug each time to have more shallow charges, but the difference between adding 5% and adding 10 or even 15% is probably trivial. I would suggest you do what fits for you.

I am in a similar situation, charging to 56% (that is the inflexion point) and driving very short distances daily. I plug in when I feel like it or when I'm down around 40%. Mostly convenience really, as I don't particularly like to plug every evening. The difference is so subtle that it doesn't seem worth the hassle.

 

[ATPMSD]

Unless you plan to keep your car for 5+ years then don’t worry about the SOC, the 50% rule you are following is not going to offer you any real benefit. So do what is the most convenient for you.

Do not be a slave to your car’s battery, you are far better off charging the car to a level that will get you though the entire day then to make multiple stops. There is really no issue charging to 90% every day and then running it down. Personally, I use 10% SOC as my bottom. This gives me a good margin so I don’t worry about range.

 

[zoomer0056]

Unless you plan to keep your car for 5+ years . . .

I'm not picking on you specifically. Many people say the same thing, that if you will keep the car a short time then don't think about the cars health long term. What about the idea of passing on the car to the next person with the healthiest battery possible? Not just for environment or the sake of not wasting because we don't have to waste, but also for resale value. A healthier battery has to be worth more. Thinking out loud here.

 

[Drinyth]

I believe you are splitting hairs. Yes, it seems to be marginally better to plug each time to have more shallow charges, but the difference between adding 5% and adding 10 or even 15% is probably trivial. I would suggest you do what fits for you.

I am in a similar situation, charging to 56% (that is the inflexion point) and driving very short distances daily. I plug in when I feel like it or when I'm down around 40%. Mostly convenience really, as I don't particularly like to plug every evening. The difference is so subtle that it doesn't seem worth the hassle.

I do understand that I'm splitting hairs and going above an beyond what is needed. But it's really not an inconvenience to me either way, so I'm happy to micromanage my charging in a way that maximizes longevity.

Unless you plan to keep your car for 5+ years then don’t worry about the SOC, the 50% rule you are following is not going to offer you any real benefit. So do what is the most convenient for you.

Do not be a slave to your car’s battery, you are far better off charging the car to a level that will get you though the entire day then to make multiple stops. There is really no issue charging to 90% every day and then running it down. Personally, I use 10% SOC as my bottom. This gives me a good margin so I don’t worry about range.

I do plan to keep my car for 5+ years (my oldest car in the garage is 8 years old and I don't have plans on replacing it anytime soon). It's likely that I'll keep the car for 10+ years (assuming it is still functional at that point) and as such, I'd like to keep the battery as healthy as possible for as long as possible.

I fully agree with not being a slave to the battery. I have no qualms about charging to any level that I need to for my convenience. I'd never purposely create a situation where I have to stop and force myself to charge mid-day solely to stay under some SoC limit.

But since I work from home, rarely travel outside the metro area, and am here most of the time, 50% is more than enough to easily get me where I need to go and back.

 

[ATPMSD]

Not just for environment or the sake of not wasting because we don't have to waste, but also for resale value. A healthier battery has to be worth more. Thinking out loud here.

When you allow battery concerns to impact how you drive the car, then I suggest you have taken this too far. One of the problems that exists with all the advice you see, and it is all very well intentioned, is they are opinions. Much of the data referred too is drawn from laboratory tests on the battery type or from how the chemistry of the battery should work, but to my knowledge none of the data comes from tests using actual Tesla battery packs. Only Tesla knows for sure and they are not telling.

Tesla’s “official” position is to keep the car plugged in and charged all of the time to 90% if not an LFP battery, or to 100% otherwise. But honestly, I think this has more to do with marketing to ensure max range is always available and less to do with battery health, again just an opinion.

I fully agree with not being a slave to the battery.

Whatever you choose to do, this is the right answer! Enjoy your car.

 

[SageBrush]

Based on what I've read, I'm sold on keeping my vehicle charged to its lowest SoC that suits my driving needs for a daily basis is what works best for me. For my needs, I'm easily able to stay at 50% for a target charge level and have more than enough capacity for my driving needs.

My question is if I make multiple daily trips, is it better to constantly plug in after each trip backup to 50%? Or to just charge once per day and let my overall daily SoC remain lower?

In other words, assuming that my charge level is set to 50%, is it better to do 3-4 x 5% charges (i.e. 45% back up to 50%)? Or to do one charge overnight of 15-20% for the day? The prior keeps my charging cycle smaller but the latter keeps my battery at a lower SoC as an average?

I realize that I may be splitting hairs here in doing what I can to maintain battery health, but I don't feel it's an hassle for me at all for me to do it whatever way is best for battery longevity. I typically just make in town trips and I work from home so am easily able to plug in between trips (with the only inconvenience being to reach over and plug in the charging cable that's right next to where my car is parked).

 

[SageBrush]

Once a day will be fine

 

[E90alex]

The car won’t even charge if it’s within a couple % of the charge limit. The effect on battery longevity may be minimal but is probably good to develop the habit of plugging in every time you park in the garage so you don’t end up forgetting one day.

 

[GtiMart]

You're slightly misinterpreting the displayed SOC, which takes into account the battery temperature to indicate how much energy can be taken OUT of the battery, with true SOC. The car will charge the battery if the true SOC is one or two percent under.

 

[Grabthar]

Tesla recommends ABC - always be charging

 

[RedY23]

Tesla recommends ABC - always be charging

Spot on Grabthar!!!

I think the only people that know the answer to the question topic here are tesla engineers. AND DRUMROLL.....the TESLA Engineers recommend to

1. Always Be Charging. (not only this keeps your car topped off but they indicate there are temperature benefits to the battery from staying plugged in).
2. Keep the car charged at 90% for daily use and 100 for long trips.
3. Get the car/battery ready for trips especially in cold weather.

I asked "a Tesla Engineer" why so many like to only top off at 80%...to "prolong battery life". Her answer was that it is BS. They used to recommend that sometime ago but now the batteries are made better and they also have more data that it does not make any statistically significant difference.

 

[ATPMSD]

Just keep in mind that a lot of what Tesla says has more to do with marketing then with engineering. Keeping the car plugged in is likely more about marketing to ensure max range is always available and less with battery health.

 

[RedY23]

Actually I respectfully dissagree. Its better marketing to have cars that last. It is why they put in the time and money to have superior battery management systems and thermal controls.
The friend I spoke to from Tesla indicated if you want battery and car to last follow their reccomendations and most critical do not drive it like a race car that it is, all the time.
For me its hopeless. I cant help but floor it at every oppertunity. Linear 0-60 acceleration in 3.5 seconds is too much fun. Guess Ill be selling it in 3/5 years.

 

[AAKEE]

In other words, assuming that my charge level is set to 50%, is it better to do 3-4 x 5% charges (i.e. 45% back up to 50%)? Or to do one charge overnight of 15-20% for the day?

The cycles themself wear a lot less than the calendar aging. The approach that give you the lowest average SOC will win the low degradation contest.

By principle, small cycles is better than large. But as calendar aging takes a bigger bite of the battery capacity than cycles, the lower the average SOC, the lower the calendar aging.
Aiming to have a low SOC overnight and to charge shortly before the next days drive is a good strategy.

 

[ATPMSD]

By principle, small cycles is better than large.

Turns out this is a highly debatable statement. On the surface of it small cycles seem better than larger ones, but you need many more small cycles to match one large one. For example, you will need five 10% cycles to match a single 50% cycle.

 

[Drinyth]

The cycles themself wear a lot less than the calendar aging. The approach that give you the lowest average SOC will win the low degradation contest.

By principle, small cycles is better than large. But as calendar aging takes a bigger bite of the battery capacity than cycles, the lower the average SOC, the lower the calendar aging.
Aiming to have a low SOC overnight and to charge shortly before the next days drive is a good strategy.

Perfect. Thanks for your reply and input. Low overnight SoC it is with charging to conclude shortly before I expect to depart.

I appreciate the research that you've put in and shared with this forum.

 

[Unclepaul]

With so many variables effecting battery health, including average state of charge, temps, how agressive you drive your car, strength of charging, time at top and bottom of the range, which chemistry you have, your charging system, Supercharger use and at what current draw, age of battery, model of battery, number and frequency of cycles etc.

As to the OPs two strategies, I would imaging both would achieve his goals, with minuscule differences between them.

A separate strategy would be to charge your batteries just before starting out. This would warm the batteries just in time for you to drive away, reducing one thermal cycle and optimizing range on your initial trip out.

 

[ewoodrick]

Based on what I've read, I'm sold on keeping my vehicle charged to its lowest SoC that suits my driving needs for a daily basis is what works best for me. For my needs, I'm easily able to stay at 50% for a target charge level and have more than enough capacity for my driving needs.

My question is if I make multiple daily trips, is it better to constantly plug in after each trip backup to 50%? Or to just charge once per day and let my overall daily SoC remain lower?

In other words, assuming that my charge level is set to 50%, is it better to do 3-4 x 5% charges (i.e. 45% back up to 50%)? Or to do one charge overnight of 15-20% for the day? The prior keeps my charging cycle smaller but the latter keeps my battery at a lower SoC as an average?

I realize that I may be splitting hairs here in doing what I can to maintain battery health, but I don't feel it's an hassle for me at all for me to do it whatever way is best for battery longevity. I typically just make in town trips and I work from home so am easily able to plug in between trips (with the only inconvenience being to reach over and plug in the charging cable that's right next to where my car is parked).

Have you read the manual for your car? What did it say?

General recommendation from Tesla or Elon, charge to 80 or 90% unless you need to go on a trip, which in that case you can charge to 100%.

Tesla built the battery to take a beating.

ALL of the studies and recommendations that you hear are from studies about other batteries, not the specific formulations that Tesla uses. The formulation makes a huge difference.

For a newer car, your batteries are designed to last over 300,000 miles.

Enjoy the car, charge as fits your lifestyle and needs. One of the few statements from Tesla, a plugged in car is a happy car.

By charging your car to only 50% you are effectively throwing half of your range away. You bought it, you paid for it, so use it!!!

Your car will lose a percentage over the first year or so, this is expected and completely normal. This occurs no matter how you charge it.

Ask the folks who recommend 50% how much range are they expecting to add to the battery. Is it a year? a month? or a mile. No one really knows.

 

[E90alex]

Have you read the manual for your car? What did it say?

General recommendation from Tesla or Elon, charge to 80 or 90% unless you need to go on a trip, which in that case you can charge to 100%.

Tesla built the battery to take a beating.

ALL of the studies and recommendations that you hear are from studies about other batteries, not the specific formulations that Tesla uses. The formulation makes a huge difference.

For a newer car, your batteries are designed to last over 300,000 miles.

Enjoy the car, charge as fits your lifestyle and needs. One of the few statements from Tesla, a plugged in car is a happy car.

By charging your car to only 50% you are effectively throwing half of your range away. You bought it, you paid for it, so use it!!!

Your car will lose a percentage over the first year or so, this is expected and completely normal. This occurs no matter how you charge it.

Ask the folks who recommend 50% how much range are they expecting to add to the battery. Is it a year? a month? or a mile. No one really knows.

Why does Tesla allow setting it down to 50% if 90% is so magical and perfect and ideal and everyone should just charge to 90%?